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The Powerful Alternative To Fine-Tuning

Y Combinator19:46

Transcription

The world is changing so quickly. This

is probably a little bit obvious, but

you should just try things and and like

every day do something with AI. Last

summer, I took a weekend and used um

GPT5 to help me build an iPhone app. I

hadn't done that in a decade. And yeah,

it's so fast and so easy. And that was,

you know, an age ago. That was like 8

months ago. Uh now it's even faster and

easier. Don't limit yourself. like

anything that you imagine, you should

just try to use AI and see how far you

can get with it and you'll be, you know,

making the world better.

Welcome to another episode of the Light

Cone. Ian Fischer is the co-founder and

co-CEO of Poetic, which is building

recursively self-improving AI reasoning

harnesses for LLMs. Previously, he spent

a decade as a researcher at Google

DeepMind and founded a mobile devtools

company through YC years ago. Welcome,

Ian.

>> Thank you. I'm so happy to be here.

>> What is Poetic? How's it different than

RL? You know, how's it different than

context engineering?

>> At Poetic, what we're building is a

recursively self-improving system. And

so, recursive self-improvement is this

uh, you know, kind of the holy grail of

AI where the AI is making itself

smarter. The core insight that we had is

that uh we could do recursive

self-improvement far faster and cheaper

than all of the other ways that people

had been proposing to do this. Uh and so

obviously I'm I can't go into details

about what that what that is um what our

particular approach is but um most of

the approaches out there involve you

know they require you to train a new LLM

from scratch and training LLMs from

scratch costs you know hundreds of

millions of dollars and takes uh months

of effort and so the

>> and then anthropic or openi will come

along and just eat your lunch in the

next model release

>> right right and you know of course

anthropic and openi and google they're

exploring train recursive

self-improvement but typically at that

level of um having the you know having

to train a new model uh for every step

of self-improvement that they do.

>> I mean that seems like actually the like

defining thing that a startup really

really wants. Like I know that I want to

take advantage of whatever the next

model is, but the second you're in

fine-tuning land, I'm spending, you

know, millions to hundreds of millions

of dollars and then guess what? like it

I just lit it on fire cuz you know the

next version of the frontier model comes

out and I'll never catch up. Whereas

like working with your systems means

that I will always have the thing that

is uh better than the thing that's out

of box and that's sort of like the holy

grail.

>> Yeah, we think that this is uh

incredibly valuable to anybody who's

building on top of uh large language

models and we don't view the uh you know

the frontier models as competitors.

They're, you know, they're the ones that

were using the stilts, you know,

building stilts to stand on top of, but

uh if we didn't have that, um that

foundational layer, then, you know,

poetic couldn't exist.

>> Yeah. I mean, being the smartest model,

uh you know, it's a game of inches

actually and like so those inches matter

a lot,

>> right? Right.

>> How do we actually get started? I mean,

you've built something that, uh,

basically any startup could use that,

uh, it's sort of like stilts really. We

have built a system that um uh can

automatically generate systems for your

particular problem that will always

outperform the underlying language

models and without kind of the massive

expense as you're saying about the

bitter lesson where you know what would

you what would you have done without

poetic you probably would have said okay

we're going to first collect a large

data set you know like tens of thousands

of examples for our particular problem

that we're working on and we're going to

fine-tune you know the best model we can

put get our hands

uh maybe that's you know one of the

frontier models or maybe it's an open

weights model doesn't particularly

matter. you're going to spend a lot of

money on that fine-tuning. The the

compute is so expensive. Uh and then at

the end of it, you have something that

uh you know works better than the thing

that you fine-tuned on top of, but by

then a new model's come out and it's

better than the thing that you

fine-tuned. You know, you fine-tuned,

you know, like 3 years ago on top of GPT

3.5 or whatever and then GPD 404 comes

out and it just blows you out of the

water. And so, are you going to do that

again or are you going to go out of

business? And like in some cases the the

latter with poetic uh what we end up

giving you is a uh you know people are

calling these things harnesses now but

you know or a gentic system or whatever

you want to call it that sits on top of

one or more language models and it just

performs better than them. Uh and when

the new model comes out that same

harness is uh perfectly compatible with

it. Uh and you don't need to change

anything to get the uh you know an even

uh bigger performance bump.

Additionally, we can, you know, continue

to optimize for this new model, whatever

the new model is that you want to use,

uh, and, you know, make it even better.

Uh, but you, you don't lose out on, you

know, hundreds of millions of dollars.

In fact, we do this so much more

cheaply, uh, than fine-tuning would cost

as well.

>> And you've done this actually a bunch of

times, right? Like I remember when you

first came out with your paper in

December of last year, uh you shot to

the top of ARC AGI V2 and then you've

done this a bunch of times for other

benchmarks too. What you know what was

that like?

>> ARGI v2 was this was kind of you us

coming out of stealth letting people

know that we could um tackle these

really hard problems. Uh and in

particular, you know, we wanted to show

that our system could generate these um

what we call, you know, we call our

system like the poetic meta system can

generate uh reasoning systems that are

um highly effective. Gemini 3 had deep

think had just come out. Uh and they

were, you know, really quite uh

dramatically at the top of the

leaderboard at 45%. Uh and two days

later we release our results where um uh

we were showing that we could get uh a

lot higher than that. Uh

>> so they come out with soda and then you

come in right above them every single

time which is like wild to see honestly.

That's what it's like to have stilt you

know like whatever model comes out you

can be taller than that one with poetic

which is like that's so awesome.

>> Yeah. So the interesting thing is that

uh we were half the cost of Gemini 3

deep think because we were building on

top of Gemini 3 Pro which is a much

cheaper model um but we still got uh in

the end a 9 percentage point improvement

on the official verification. So they

were at 45% and we and like 70s

something dollars and we were at 54% and

$32 per problem.

>> So recently you guys just announced some

incredible results for humanity's last

exam. Can you tell us more about those?

>> Humanity's last exam is a a set of 2500

really really hard questions written by

experts in uh many different domains.

They're they're meant to be uh

challenging even for uh PhDs in those

fields. AI hasn't passed it yet. Uh but

we got to 55% which is almost two

percentage points higher than the the

previous uh state-of-the-art which came

out just last week uh from uh Anthropic

with Claude Opus 4.6. They got 53.1% and

we got 55% on it.

>> And one thing that uh humanity last exam

doesn't publish is the cost of getting

those results. In your case, this run

was done with less than around six

figure. How much was it?

>> We didn't publish any uh cost for this,

but I can say that the the optimization

costs us less than 100k. Yeah.

>> Which is impressive because each of

these big foundation modeled train runs

are in the hundreds of millions of

dollars. And you guys, as a company,

you're only seven people.

>> That's right. Yeah. Yeah. Seven uh seven

research scientists and research

engineers. Yeah.

>> That's impressive. And I think the thing

that's very interesting about your

approach is sort of taking a very

scientific approach to the emergent

behaviors that a lot of the best

founders are doing with models. I think

a lot of uh founders that get very good

results for agents, they treat the

underlying model as a common layer that

you can switch in between. And there's

certain tasks for example for GPD 5.2

two like very hard to verify bugs gets

sent to that versus architecture that

gets sent to claw 4.6 six, but you're

kind of doing this automatically instead

of having a human conducting is uh very

impressive. I think there's something

more special going on underneath. Can

you tell us a bit about how it works?

>> Yeah, it sounds magical. So, what can

you tell us?

>> Right. You're you're So, you're getting

at a core a really core thing. You know,

these harnesses, they are um code,

prompts, data, you know, built on top of

one or more language models, right? And

so this is something that in principle

you can build by hand um or with like

cloud code or whatever. But uh in in

practice it takes a lot of work to do

these to to you know have all the

insights uh to make this uh to make

these work well. And so the core

technology that we've developed at

poetic is uh recursive self-improvement.

So we we have a recursively

self-improving uh system which we call

the poetic meta system. the output of

that system is systems that solve hard

problems. Um where a hard problem is you

know something that you if you gave it

to GPT52

uh it would struggle to give you a

reliable robust result you know just to

use an example. So this is a a very big

advantage for us. We can generate these

systems in a much more automated manner.

uh which means that we can do it much

more quickly and much more cheaply than

if you hired a team yourself to try to

make um your own you know your own agent

to solve your particular task. But not

only that um since you know this is

really an automated optimization

process. If you already have done that

work you you know you're a you're a

startup that's like going after a

particular vertical and you've put

together you know you think you

understand your your problem pretty

well. You've put together your agent and

you you uh you know maybe it's working

pretty well but you know you can get

something better or you really need

something better. Um then you can bring

that to us uh and we can optimize uh

that entire agent or pieces of that

agent. So we could optimize just the

prompts, just the reasoning strategies.

Uh there's a lot of different things

that we can do uh depending on your

particular needs.

>> It sounds like this is a complete

different paradigm than RL because we

went through the scurve of regular

pre-training

RL with when OpenAI released 01 and now

this feels like a new one. It sounds

special. It sounds it rhymes a lot with

RNN's

>> which is a whole different paradigm than

than RL, right? It's going to depend on

the particular task, the particular type

of problem that we're going after that

we're trying to solve. Um, and the

underlying models that we're working

with. But, uh, effectively you could say

like each model or each set of models

that we're working with will have it

their own uh, scurve. The poetic system,

the poetic meta system itself is also

going to have its own scurve. And so as

the poetic meta system gets better and

as the underlying models get better, you

you'll find that the uh you know the

S-curve that you're dealing with keeps

shifting higher and higher until

ultimately either you saturate or like

>> reach AGI.

>> Yeah. Reach AGI, reach super

intelligences. Yeah.

>> Given its stilts, you might like hit the

ceiling first then.

>> That's the goal, right? Yeah,

>> you want to hit the ceiling first with

>> I think a lot of startups that we work

with um and then in my spare time I you

know do a bunch of context engineering

and then the thing is we're sort of like

tuning it tuning evals tuning like we're

context stuffing ourselves. What does

that even feel like to have a you know

recursively self-improving version of

like prompt engineering and context

engineering? we don't spend a lot of

time looking at the particular data that

we're working with. Uh instead, we're

letting the poetic meta system look at

that data and and so like the meta

system, you know, if it if it thinks

that it needs to put more things into

context, it do more context stuffing or

whatever, it'll it'll do that. If it

needs to like generate a bunch of

examples um uh to get the get better

performance, it'll do that for you,

right? It it was pretty interesting to

look at the um prompt outputs in

particular I'd say for ArcGI in that you

know I think you can read those and say

well that's not what a human would have

written uh pretty clearly and and it's

you know there's some unexpected stuff

and you know it made some really simple

examples and one of the examples is

actually wrong but we didn't change it.

We're like well this is you know this is

the thing that it output we'll just

leave it be. um you know we don't want

to go in and monkey around with things

and so historically in machine learning

you always you know is like the the rule

was you have to know your data set

really well um but now we're kind of

outsourcing that to the AI itself where

the AI is it's the AI's job to

understand the data set and figure out

where are the failure modes um and where

are the kind of robust reasoning

strategies that uh the model that that

the agent could uh use um to get better

performance.

>> How much of it is like much you the

output is much better prompts and then

how much of it is like the harness

itself uh context stuffing or

summarizing in the right way or

reranking in the right way so that like

you you have some number of like mega

LLM calls and then how do you get the

most out of um each of those calls?

>> Yeah. And so that definitely varies per

problem. But uh what we've seen, in

fact, our our last paper at DeepMind was

not doing this recursive self-improving

stuff, but we were um we were showing

that you could build these harnesses um

manually to solve really hard problems.

And what we saw is there is that uh you

know, we manually optimized the prompts

really hard for these very hard

problems. And that got us a little bit

of the way uh in this particular case.

you know the the hardest the hardest

task we were working on we got like to

5% performance with Gemini 1.5 flash

this was a while ago and then when we

added on the the reasoning strategies we

went from 5% to 95%

>> uh and so this is typically what we see

you know like everybody's out there kind

of doing some amount I wouldn't say

everybody but many people are out there

kind of doing some amount of automated

prop pro prompt optimization you know

Jeepa is this very popular paper

everybody's kind of implementing that

that will get you some performance

improvements, but it's very far from uh

everything that you can get uh if you

actually think about these reasoning

strategies that are really going to be

written in code rather than in in just

better prompts.

>> So if startups want to use poetic to put

their agent on stilts, what should they

do?

>> Yeah, so right now uh we haven't

released anything yet, but uh if you go

to poetic.ai, AI. Uh there is a button

you can click to get uh sign up for

early access. And if you're a startup uh

or a company who has a really hard

problem uh and you've tried everything

that you can to make it uh reliable and

robust and you just can't get all the

way there, you you need something more,

then uh let us know. We're looking for

problems like that. Uh so just tell us

tell us what it is that you're working

on and uh we'll reach out. You'll be the

first to know when we're when we're

ready to work with you. I mean, if

you're at the top of um humanity's last

exam, then I mean, that's that's pretty

big. So, it's you're all you're already

all the way out there at soda and then I

guess the stilts basically let any

agentic company become soda.

>> That's the idea. Yeah. Yeah. And you

know, we view the ArcGI results and the

humanities last exam results as showing

kind of two different uh capabilities

that we have. We can really improve your

reasoning and we can really improve uh

deep knowledge extraction uh from these

models

>> and then you're just totally vaccinated

against the bitter lesson.

>> Exactly.

>> YC's next batch is now taking

applications. Got a startup in you?

Apply at y combinator.com/apply.

It's never too early and filling out the

app will level up your idea. Okay, back

to the video.

>> Slight sort of change change of topic,

but something I was curious about. Uh so

you arrived at Google over a decade ago

when they acquired your first YC startup

at portable. A portable was it's porting

mobile apps crossplatform right like

Android or or whatever. It's quite

different to um recursive self-improving

AGI. Um how did you make that leap? What

happened once you got to Google? Um what

made you think that you maybe wanted to

shift out and do something different?

And just would love to hear that story.

the acquisition uh was this amazing

opportunity to um reflect on what I

really wanted to be doing next, right?

Like Google was in, you know, itself is

a place where you can do so many

different things. Uh so I spent some

time thinking about um where uh where I

wanted to go next in in uh in my

journey. I realized that the problems

that I was most excited about were

really actually AI and uh and robotics.

Um and the best people in the world,

many of them in those fields were at

Google at the time. Uh and so I went and

talked to them. they uh let me come join

you know a new AI robotics team uh in

Google research which was this amazing

opportunity for me since that wasn't my

background my background was like uh

computer security and then this

crossplatform mobile you know it's

systems building uh stuff I was able to

join this team and I I'll tell you the

truth that uh I very quickly realized

that uh hardware is hard uh and I didn't

really want to be doing robotics is more

aspirational at that moment

uh but I was really um uh passionate

about machine learning. So I just uh uh

made a very hard switch into just doing

machine learning research uh and did

that for you know about a decade at

Google and and then Google and then deep

mind.

>> What's maybe some advice that you have

today for engineers who want to get into

sort of more of the AI side probably the

applied AI and build startups around AI

like how should they think about that?

You know, the world is changing so

quickly. This is probably a little bit

obvious, but you should just try things

and and like every day uh do something

uh do something with AI. Always try to

push yourself to find the boundaries of

what they're capable of. Uh and uh and

build the things that you that you want

to build, right? Um, even even for me,

you know, last summer I took a weekend

and used um GPT5 to help me build an

iPhone app. I hadn't I hadn't done that

in a decade. So fast.

>> Yeah, it's so fast and so easy. And that

was, you know, that was an, you know, an

age ago. That was like eight months ago.

Uh, now it's even faster and easier.

Don't limit yourself. Like anything that

you imagine, you should just try to use

AI and see how far you can get with it

and you'll be, you know, making the

world better. That's all we have time

for today, but Ian, thank you so much

for giving us all Stilts. Uh, we can't

wait to use it at YC. I can't wait to

use it for Gary's list. I mean, there's

just so much to do. So,

>> yeah, thank you for having me. This was

a lot of fun.